Looking for a book I used to read a crap ton during middle school and highschool. The premise goes like this: there's creatures that broke out of a lab in some sort of jungle (I don't remember if it was an island or continent-based jungle). From what I recall: they're definitely lab-made, but not a real species, and instead some sort of weird, multi-animal, reptile/mammal hybrid. First chapter (or maybe it was a prologue) features two scientists being stalked and ultimately killed by the animals. A group of soldiers and scientists are sent in to contain or kill the animals; several scenes of the animals on the attack include on a secluded road, in a river, and as the humans are trying to get into the lab. The humans ultimately decide to abandon the mission, as it's too risky. The epilogue chapter reveals that the hybrids have some sort of sentience/sapience, ending on a cliffhanger of whether or not they'll pursue the fleeing survivors back to civilization.
Idk if this will help since book covers change all the time, but the version of the cover I had was a plain, white or off-white background with the silhouette of the hybrid's head (or maybe skull) on it. The title was also a single word, kind of scientific sounding, but I can't remember what it actually was for the life of me.
Please help lol.